This invention relates to a vehicle passenger seat having an inner frame and an outer frame, which inner frame and outer frame are intended to perform separate energy absorbing functions in the event of an impact, and a single upholstery cover compatible with the inner and outer frames, which upholstery cover is provided with a fabric seam that is intended to absorb additional energy upon separation. Specifically, it is intended to complement a vehicle passenger seat of a type known in the industry, and provide a cost-efficient means of improving the energy absorbing characteristics thereof.
Designers of vehicles used to transport multiple passengers, particularly passengers who are minors, are posed with a unique challenge. Multitudes of passengers, especially minors, cannot be relied upon to securely fasten seat belts, or to refrain from unbuckling them once they are buckled. In order to compensate for this, and to ensure that passengers are restrained in the event of an impact, designers of these vehicles have adopted the practice of “compartmentalization”. The practice of “compartmentalization” is based upon providing only a small distance between the seated passenger and the seat-back directly in front of him or her, wherein that person can develop only a limited velocity relative to the rapidly decelerating vehicle. Further, the practice also depends upon providing a seat-back that can absorb the inertial energy of that person without injury to him or her. The National Highway Traffic Safety Administration, DOT (NHTSA) has codified this practice into 49 C.F.R. Section 571.222 (FMVSS 222), which sets forth the requirement that the rear side of the seat provide an impact barrier in which the seat-back bends or deforms when subjected to the force of occupants impacting it during a deceleration event. The rate, force, and maximum amount of deflection required are set forth in that title.
The code applicable to school busses at this time does not require the use of any sort of active restraint such as a two-point passenger restraining lap belt or a three-point passenger restraining lap belt and torso harness combination. Yet there is a demand for active restraints by certain customers and organizations. In order to accommodate this demand, manufacturers of school busses have begun to offer both types. The addition of three-point passenger restraining lap belt and torso harness combinations to passenger seats designed to meet the requirements of 49 C.F.R. Section 571.222 (FMVSS 222) has special implications for the ability of that passenger seat-back to absorb energy. Specifically, the requirements for passenger seats having three-point passenger restraining lap belt and torso harness combinations are set forth in 49 C.F.R. Sections 571.209 and 571.210 (FMVSS 209 and FMVSS 210). That title sets forth a test procedure and requirements for a minimum loading strength of the three-point passenger restraining lap belt and torso harness combination, as well as for the anchorage points thereof.
The difficulty lies in meeting both the energy absorption requirements for the seat-back of 49 C.F.R. Section 571.222 (FMVSS 222) and the seat belt anchorage loading strength requirements of 49 C.F.R. Section 571.209 and 571.210 (FMVSS 209 and FMVSS 210). This difficulty is most pronounced in the scenario wherein a seat occupant is buckled into a three-point passenger restraining lap belt and torso harness combination, and the occupant of the seat immediately behind him or her is not buckled in. The solution increasingly employed by manufacturers of such school busses, utilizes a passenger seat with an inner and an outer frame. The inner frame is designed to articulate forward a certain amount under the initial loading of the passenger belted into the seat, before resisting further forward movement. The outer frame remains in its initial position, until the unbelted passenger in the seat immediately to the rear impacts it, at which time it performs its energy absorbing function. Such seat designs are not new, and are set forth in patents such as U.S. Pat. Nos. 6,123,388 and 6,485,098.
In order to accommodate the relative movement between the inner and outer seat frames in the event of an impact, the passenger seat in question is typically provided with separate upholstery covers and padding for each section, both inner and outer. This means that the seat has a crevice where the two sections abut, which encourages vandalism and tampering by passengers, especially by minors. Further, it means that when seat upholstery becomes torn or cut, the seat must be at least partially disassembled in order to replace the upholstery.
Previous to the invention disclosed herein, the inner frame of a passenger seat having an inner and outer frame was not designed to absorb energy during the duration of its articulation, other than a singular event, such as the separation of a frangible member, whereby the inner frame initially separated from the outer frame. This event was based on the initial impact of the seat occupant against the three-point passenger restraining lap belt and torso harness combination. Commonly, no separation event was employed at all, relying rather upon the seat cushion to locate the inner frame in its unarticulated position, and only engaging to significantly resist forward movement at the limit of articulation.